Methanol extract of wheatgrass induces G1 cell cycle arrest in a p53-dependent manner and down regulates the expression of cyclin D1 in human laryngeal cancer cells-an in vitro and in silico approach

Background: Deregulation of cell cycle has been implicated in the malignancy of cancer. Since many years investigation on the traditional herbs has been the focus to develop novel and effective drug for cancer remedies. Wheatgrass is a medicinal plant, used in folk medicine to cure various diseases. The present study was undertaken to gain insights into antiproliferative effect of methanol extract of wheatgrass. Materials and Methods: Cell viability was assessed via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Lactate Dehydrogenase assays. Cell cycle was analyzed by flow cytometry. Western blot was performed to determine the p53 and cyclin D1 levels. In silico docking interaction of the 14 active components (identified by high-performance liquid chromatography/gas chromatography-mass spectroscopy) of the methanol extract was tested with cyclin D1 (Protein Data Bank ID: 2W96) and compared with the reference cyclin D1/Cdk4 inhibitor. Results: Methanol extract of wheatgrass effectively reduced the cell viability. The cell cycle analysis showed that the extract treatment caused G ₁ arrest. The level of cyclin D1 was decreased, whereas p53 level was increased. Molecular docking studies revealed interaction of seven active compounds of the extract with the vital residues (Lys112/Glu141) of cyclin D1. Conclusion: These findings indicate that the methanol extract of wheatgrass inhibits human laryngeal cancer cell proliferation via cell cycle G ₁ arrest and p53 induction. The seven active compounds of the extract were also found to be directly involved in the inhibition of cyclin D1/Cdk4 binding, thus inhibiting the cell proliferation.